Communicating ancillary information associated with a plurality of audio/video programs

ABSTRACT

A method and apparatus of communicating audio/video programs (e.g., television content associated with a plurality of channels) includes receiving the audio/video programs over a transport medium. A stream of ancillary data portions associated with a plurality of audio/video programs (e.g., a plurality of television channels or transport stream programs) may be received over a separate delivery mechanism. The ancillary data may include announcements associated with enhancement data according to an Advanced Television Enhancement Forum Specification, for example. One of the audio/video programs is tuned to, with one or more ancillary data portions located and identified with the tuned audio/video program. A special announcement in the ancillary data portions delivered to an expected location is used to locate announcements for the tuned audio/video program.

BACKGROUND

[0001] The invention relates to communicating ancillary informationassociated with a plurality of audio/video programs, such as televisioncontent associated with a plurality of channels.

[0002] Ancillary information, such as program sub-titles, emergencymessages, closed caption messages, and program guide information, may betransmitted with regular television content. More recently, other typesof ancillary information that may be sent with television contentinclude enhancement data such as web pages, multimedia information, orother digital data files. Ancillary information may be sent in thevertical blanking interval (VBI) of an analog television broadcastsignal. Alternatively, the ancillary information may be sent withdigital television content over a digital transport medium.

[0003] Various standards exist that provide for transmission ofancillary information with television content. One standard is theAdvanced Television Enhancement Forum (ATVEF) Specification, DraftVersion 1.1r26, dated Feb. 2, 1999. The ATVEF Specification is designedto provide for transmission of enhancement data along with televisioncontent in both analog and digital systems, such as cable systems,satellite systems, terrestrial systems, and so forth. The combination ofthe enhancement data and the television content may be referred to asenhanced television content. Enhanced television content provides moreinformation and options to viewers. For example, a viewer may bepresented with the option of viewing advertisements, educationalinformation, and so forth, while watching regular televisionprogramming.

[0004] Transmission of enhanced television content, however, mayincrease bandwidth requirements of the transport medium between thetransmission source and receiving sites. Thus, a need exists to providefor solutions that address bandwidth limitations of transport media aswell as provide for greater flexibility in the transmission of suchancillary information.

SUMMARY

[0005] In general, according to one embodiment, a method ofcommunicating audio/video programs includes receiving the audio/videoprograms over a transport medium. A plurality of ancillary informationstreams associated with a plurality of audio/video programs arereceived. One of the audio/video programs is tuned to, with one or moreof the ancillary information streams identified as associated with thetuned audio/video program.

[0006] Other features and embodiments will become apparent from thefollowing description and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIGS. 1A and 1B are block diagrams of embodiments of informationdelivery systems.

[0008]FIG. 2 is a block diagram of a transport operator system,receiving system, and server according to one embodiment in theinformation delivery systems of FIGS. 1A and 1B.

[0009]FIGS. 3A, 3B, 4, and 5 illustrate transmission and receipt ofaudio and video content and associated ancillary information accordingto an embodiment.

[0010]FIG. 6 is a flow diagram of a transport routine according to oneembodiment.

[0011]FIG. 7 is a flow diagram of a routine or routines adapted toreceive ancillary information according to one embodiment.

DETAILED DESCRIPTION

[0012] In the following description, numerous details are set forth toprovide an understanding of the present invention. However, it is to beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments may be possible. Forexample, although reference is made to the Advanced TelevisionEnhancement Forum (ATVEF) Specification, Draft Version 1.1 r26, datedFeb. 2, 1999, it is contemplated that other versions of the ATVEFSpecification as well as other standards and techniques for transmissionof ancillary information with content that includes audio data or videodata (e.g., television content) may be included in further embodiments.

[0013] Referring to FIG. 1A, an information delivery system 10 accordingto one embodiment includes a content creator 12, a transport operatorsystem 14, and a plurality of receivers 16. The receivers 16 may belocated at various receiving sites, including homes, offices,entertainment facilities, or other locations. The content creator 12originates enhancement data (or other type of ancillary information) andtelevision content (or other type of content including audio and/orvideo data) to be transmitted by the transport operator system 14.Alternatively, the content creator 24 may create enhancement data withtelevision content provided by another source to the transport operatorsystem 14. Enhancement data may include graphics (e.g., web pages,multimedia information, or other digital data files), presentationlayout, and synchronization information. The combination of theenhancement data and television content is referred to as enhancedtelevision content.

[0014] The transport operator system 14 provides an enhanced televisioncontent delivery infrastructure that may include terrestrial, cable,satellite, or other types of transmission facilities (either analog ordigital). The television content and enhancement data may be transmittedover a transport medium 22 which may be a terrestrial, cable, satellite,or other type of link, to the receivers 16. The receivers 16 may includetelevisions, set-top boxes, personal computers, or other types ofsystems adapted to receive television content and associated enhancementdata.

[0015] As used in this description, the term audio/video (A/V) contentis intended to include any type of audio and/or video data that may betransmitted or distributed to one or more receiving sites forpresentation to viewers and/or listeners. As used here, A/V content mayrefer to content that may include both an audio and a video portion orone of an audio or video portion. Further, ancillary information otherthan enhancement data may be transmitted with the A/V content. Forexample, ancillary information may include program sub-titles, emergencymessages, closed caption messages, and program guide information.

[0016] The receivers 16 may further be coupled to a secondary link 20which may be a data delivery communications channel such as theInternet, a DOCSIS network (which is an interface for cable modems), orother communications link (whether uni-directional or bi-directional).DOCSIS stands for Data Over Cable Systems Interface Specifications, andis described in DOCSIS, Version 1.0, dated March 1998, as provided bythe International Telecommunication Union (ITU). The secondary link 20may be coupled to the transport operator system 14 and/or to one or moreservers 18. According to some embodiments, portions of enhancement dataassociated with the A/V content transmitted over the transport medium 22may be communicated over the secondary link 20 from the transportoperator system 14, the one or more servers 18, or some combination ofsuch systems.

[0017] In an alternate embodiment, another type of secondary data pathcan be part of the A/V transmission itself, but not tightly tied to aparticular A/V channel. For instance, in MPEG-2 based systems like ATSC(Advanced Television Systems Committee) or DVB (Digital VideoBroadcasting), transport stream programs correspond to what is commonlythought of as TV channels. MPEG stands for Moving Picture Experts Group,and the MPEG-2 standard is described in ISO/IEC 13818-1 (MPEG-2Systems), ISO/IEC 13818-2 (MPEG-2 Video) and ISO/IEC 13818-3 (MPEG-2Audio), dated in 1994 and provided by the International Organization forStandardization (ISO) and the International Electrotechnical Commission(IEC). A description of ATSC may be found in “Guide to the Use of theATSC Digital Television Standard,” dated October 1995. DVB standards maybe available from the web site {http://www.etsi.org}.

[0018] These transport stream programs can contain audio, video and data(e.g., ancillary information), with all of them tightly associated withthat single transport stream program. When a user tunes to the transportstream program, the receiving device knows the audio, video, and datathat are associated because they are marked as all being part of thesame program. In addition, other transport stream programs can becreated that contain no audio or video, only data. In this case,ancillary information associated with a plurality of audio/videoprograms could be carried in a single data-only transport streamprogram. This creates the same situation as if that ancillary data wascarried outside the transport that carries the audio/video program. Datathat is intended to be associated with a particular audio/video programis transported separate from it and instead may be multiplexed onto asingle delivery mechanism (e.g., a data-only transport stream program)that carries ancillary information for many audio/video programs. Theproblem then becomes being able to re-associate ancillary informationwith the proper audio/video program at the receiving end.

[0019] One standard for describing transmission of enhancement data withtelevision content is the ATVEF specification, with one versiondescribed in ATVEF Specification, Draft Version 1.1r26, dated Feb. 2,1999. Enhancement data may be transmitted in a number of different waysfrom the transport operator system 14 to the receivers 16, depending onthe type of transport medium 22. For example, with an analog transportmedium such as the National Television System Committee (NTSC) Standardof the Electronics Industries Association, portions of the enhancementdata may be sent in the vertical blanking interval (VBI) of the NTSCtransmission. A description of NTSC may be found in Keith Jack, “VideoDemystified: A Handbook For the Digital Engineer,” HighText Publications(2d Ed. 1996). Other types of transport media (analog or digital) mayprovide different mechanisms of communicating the enhancement data.

[0020] Enhancement data according to the ATVEF Specification may includeenhancements each having the following components: an ATVEFannouncement, a resource, and a trigger. The three components may betransmitted using Internet Protocol (IP) multicast to the receivers. AnIP multicast standard is described in Request for Comment (RFC) 1301,entitled “Multicast Transport Protocol.” RFCs may be available atwebsite address {http://www.ietf.org/rfc.html}.

[0021] Generally, an ATVEF announcement indicates that enhancement datais being transmitted, a resource includes one or more files that containthe enhancement data, and a trigger synchronizes the enhancement datawith the TV transmission. An announcement may describe the location ofboth the resource stream and the trigger stream. For each television(TV) channel, one or more enhancements may be offered as choicespresented to the user, who can select which of the enhancements, if any,to view. The ATVEF Specification may utilize a one-way transmissionprotocol (the Unidirectional Hypertext Transfer Protocol or UHTTP,described in the ATVEF Specification) to deliver resource data.

[0022] The announcements, resources, and triggers associated with an A/Vchannel may be delivered at about the same time as and with thetransmission of the A/V content on that channel. Conventionally, foreach enhancement, the resource stream may be delivered along with theannouncement, with the resource stream stored locally in the receiver16. If a viewer so desires, the enhancement data can be retrieved at thereceiver from local storage for viewing.

[0023] Conventionally, ATVEF announcements arrive at an expectedlocation, such as a predetermined Internet Protocol (IP) address andport. The Internet protocol is described in RFC 791, entitled “InternetProtocol,” dated September 1981. The locations of the resource andtrigger streams specified in the ATVEF Specification may be described asIP addresses and ports where the resources and triggers may be found.The ATVEF announcement may be a Session Description Protocol (SDP)announcement, as described in RFC 2327, entitled “SDP: SessionDescription Protocol,” dated April 1998.

[0024] In current ATVEF systems, the enhancement data includingannouncements are delivered with the A/V content associated with each TVchannel. However, announcements for multiple TV channels are not groupedfor arrival at the ATVEF announcement IP address and port in thereceivers 16, as the one or more announcements of the currently tuned TVchannel are received at the ATVEF announcement IP address and port alongwith the A/V content stream of the currently tuned TV channel. Thus,conventionally, when tuning from one TV channel to another, the receiverassumes that the source of the data network changes correspondingly,that is, only announcements for the currently tuned TV channel flow onthe announcement IP address and port. For example, when a receiver istuned to channel B, the enhancement data of channel B is received at theannouncement IP address and port but not enhancement data associatedwith other channels. According to the current ATVEF Specification, ATVEFannouncements for channels other than the currently tuned channel cannotarrive in the ATVEF announcement IP address and port. The enhancementdata is thus tightly coupled to the A/V content associated with each TVchannel so that the receiver can easily associate the enhancement datawith the A/V content of the currently tuned TV channel in a conventionalATVEF system.

[0025] To provide for greater flexibility and/or to alleviate bandwidthconcerns of the transport medium 22, some embodiments of the inventiontransmit (using IP multicast) enhancement data associated with multipleA/V channels (e.g., TV channels) over a link that is separate from thetransport medium used to transmit A/V content (or, alternatively, thatis part of the same delivery mechanism as the A/V content but is notassociated with any A/V channel, e.g., an MPEG-2 transport stream withancillary information in a data-only program separate from the A/Vprograms). The separate delivery mechanism to deliver the A/V contentmay be a separate transport stream or a separate link 20 such as ageneral purpose data link or some other type of communications link.Thus, according to some embodiments, enhancement data is separated fromthe A/V data at the transport operator system 14 (or alternatively, atanother source), with the A/V content transmitted over the transportmedium 22 and the enhancement data transmitted over the secondary link20 (or a separate transport stream).

[0026] In the ensuing description, reference is made to receivingenhancement data received over the secondary link 20; however, it iscontemplated that the enhancement data or other type of ancillaryinformation may be received over a separate transport stream such asthat used with MPEG-2 delivery systems. In addition, reference is madeto tuning to a specific A/V channel (e.g., TV channel) at the receivingend. It is contemplated, however, that the receiver system can be tuninginstead to one of the A/V transport stream programs in an MPEG-2 basedsystems.

[0027] Thus, generally, tuning to an A/V program may include tuning toA/V channels (e.g., TV channels), to transport stream programs (e.g., inan MPEG based system), or to other separations or segments of A/Vcontent. Also, associating ancillary information with an A/V program canthus refer to associating ancillary information with an A/V channel, atransport stream program, or other A/V separations or segments.

[0028] In accordance with some embodiments, the enhancement dataassociated with multiple A/V channels may be grouped and stored in thetransport operator system 14 and/or the one or more servers 18 andmultiplexed into a transmission stream on the secondary link 20.Consequently, according to some embodiments, enhancement data associatedwith multiple A/V channels may be combined into a transmission stream onthe secondary link 20. At the receiving end, the combined stream ofenhancement data is separated and associated with a currently tuned A/Vchannel.

[0029] In accordance with some embodiments, indications (referred to asspecial announcements) may be transmitted over the secondary link 20along with the enhancement data to aid in the association of enhancementdata with the tuned channel. In a conventional ATVEF system, suchspecial announcements are not employed because enhancement data istightly coupled with the A/V content. Upon receipt of the specialannouncements, each receiver 16 determines the A/V channel that thereceiver is tuned to and identifies the special announcement associatedwith the tuned channel. The special announcement includes dataidentifying locations of one or more ATVEF announcements associated withthat A/V channel. At the receiving end, instead of ATVEF announcementsarriving at the expected location (e.g., predetermined IP address andport), the special announcements arrive at the expected location. Usinginformation in a special announcement, each receiver 16 can then locatethe one or more ATVEF announcements received over the secondary link 20and associate them with the tuned channel. From the retrieved ATVEFannouncements, locations of resource files and triggers can then beconventionally determined for retrieval and presentation. The resourcefiles of the enhancement data can then be combined with the A/V contentfor presentation (audio or video presentation or both).

[0030] Thus, effectively, some embodiments of the invention separate A/Vcontent and enhancement data at the source (e.g., the transport operatorsystem 14). The A/V content is transmitted over the transport medium 22,while the enhancement data (along with special announcements) associatedwith multiple A/V channels are combined and multiplexed onto a separatetransmission stream. At the receiving end (e.g., receivers 16), thecombined enhancement data are separated (demultiplexed) and associatedwith a currently tuned A/V channel.

[0031] Referring to FIG. 1B, an alternative embodiment of an informationdelivery system 10A is illustrated. The system 10A includes a contentcreator 12 and a transport operator system 14 to transmit A/V contentwith enhancement data over the transport medium 22. Unlike theinformation delivery system 10 of FIG. 1A, the system 10A includesdistribution systems 50 and 51, coupled to receive A/V content andenhancement data from the transport operator system 14. The distributionsystems 50, 51 may include geographic regional centers, for example,adapted to receive enhanced TV content and to distribute the contentlocally in a predefined geographic region. Each distribution system 50or 51 transmits A/V content and enhancement data to receivers 17 or 19,respectively. In addition, the receivers 17 or 19 are coupled byrespective secondary link 21 or 23 (e.g., Internet, DOCIS link, or othertype link) to respective distribution system 50 or 51.

[0032] In the embodiment of FIG. 1B, the distribution system 50 or 51separates the AN content from the enhancement data, with the AN contentsent over transport medium 52 or 53 and combined enhancement dataassociated with multiple AN channels transmitted over data link 21 or23. Alternatively, the enhancement data may be transmitted by one ormore servers 25, 27 over the secondary links 21, 23.

[0033] Special announcements may also be sent by the distribution system50 or 51 over the secondary link 21 or 23. As with receivers 16 in theFIG. 1A embodiment, the receivers 17 or 19 are able to demultiplex thecombined enhancement data (sent along with the special announcements) toassociate enhancement data with a tuned AN channel.

[0034] Referring to FIG. 2, components in the transport operator system14, receiving system (receiver 16, 17, or 19) and the server 18 in thesystem 10 of FIG. 1A are illustrated. With some modifications, thedistribution system 50 and 51 may have similar components as thetransport operator system 14. The transport operator system 14 mayinclude a receiving port 102 to receive information from the contentcreator 12 over a link 24. The received enhancement data may be providedto a controller 106 in the transport operator system 14. AN content maybe received with the enhancement data through port 102 or through aseparate AN receive port (not shown). The controller 106 may be rununder control of a software routine 108 (referred to as a transportroutine). The transport routine 108 may initially be stored in a storagemedium 104 and loaded by the controller 106 for execution. Instructionsand data of the transport routine 108 may also be stored in the storagemedium 104. According to some embodiments, the controller 106 may beadapted to separate the AN content from the enhancement data beforeseparate transmission of the AN content over the transport medium 22.The controller 106 may also create special announcements to betransmitted with enhancement data over a separate link (e.g., link 20).The enhancement data and special announcements may be stored in astorage medium 113, which may be transmitted over the secondary link 20through a transceiver 112. Alternatively, the enhancement data andspecial announcements may be transmitted over the transport medium 22with the A/V content but in a separate transport stream program. In thelatter embodiment, different parts of the transport routine 108 (oralternatively, different routines) may handle transmission of both theA/V content and the enhancement data and special announcements. Thetransceiver 112 may be a telephone modem, a cable modem, or any othertype of analog or digital transceiver or transmitter adapted tocommunicate over the secondary link 20.

[0035] Enhancement data may be stored in a storage medium 126 in theserver 18 in addition to or instead of the enhancement data stored inthe transport operator system 14. The server 18 further includes atransceiver 124 coupled to the secondary link 20 and a control device128. More than one server 18 may be coupled to the secondary link 20 tostore additional enhancement data. Alternatively, a plurality of servers18 may be coupled to the receivers 16 over separate links.

[0036] In the receiving system (receiver 16, 17, or 19), a receivercircuit 114 (e.g., a TV tuner card) is adapted to receive content overthe transport medium 22 and a transceiver 116 is adapted to communicateover the secondary link 20. The receiving circuit 114 may be associatedwith an A/V device driver routine 130 that forwards the received A/Vcontent to application software adapted to process and present the A/Vcontent in the receiving system. The transceiver 116 may be associatedwith a network device driver 132 to receive enhancement data from thelink 20.

[0037] In one embodiment, the network device driver 132 may sendreceived data to a TCP/IP (Transmission Control Protocol/InternetProtocol) stack 134. TCP is described in RFC 793, entitled “TransmissionControl Protocol,” dated September 1991. Data flows through the TCP/IPstack 134 to application software, including an enhancement routine 138for receiving and processing enhancement data and a special announcementroutine (SA routine) 136 to receive and process special announcements.In an alternative arrangement, the SA routine 136 may be part of theenhancement routine 138. The application routines, device drivers, andother routines or programs may be executable on a controller 120. Suchroutines or programs may be initially stored in a storage medium 118 andloaded by the controller 120 for execution. The SA routine 136 iscapable of associating enhancement data received over the secondary link20 to the currently tuned A/V channel. The SA routine 136 may thencombine the associated enhancement data with the A/V content of thecurrently tuned TV channel for presentation. Alternatively, theenhancement data and special announcements may arrive in a separatetransport stream program (e.g., such as those in MPEG based systems)over the transport medium 22, in which case it may be different parts ofthe SA routine 136 (or different routines) that process receipt of theenhancement data and A/V content.

[0038] Referring to FIG. 6, a process according to one embodimentperformed in the transport operator system 14 by the controller 106(under control of the transport routine 108) is described. Enhancementdata for different A/V channels are received (at 202) by the controller106. The enhancement data for the different TV channels, which may be inthe form of IP datagrams, for example, may then be combined (at 204) andstored in the storage medium 113. Alternatively, the enhancement datamay be communicated to the server 18 for storage and transmission overthe link 20. Resources and triggers associated with the different TVchannels are stored at their respective IP addresses. The controller 106detects presence of announcements when they appear at the ATVEFannouncement address and port in the transport operator system 14. Theannouncements are separated out onto different IP addressescorresponding to the A/V channels, with one IP address assigned for theone or more ATVEF announcements associated with each A/V channel. Suchannouncements are not sent along with the A/V content on the ATVEFannouncement address and port, as conventionally done, but instead arestored at a different announcement IP address.

[0039] The controller 106 next resolves (at 206) any IP addressconflicts that may occur among IP datagrams containing resource andtrigger streams. If a clash in IP addresses exists for IP datagrams ofthe resource and trigger data for different TV channel sources, the IPaddresses of the datagrams may be changed to avoid collision.Conventional techniques exist to detect and resolve IP addressconflicts. Alternatively, conventional techniques also exist forassigning IP multicast addresses (e.g., static owned address allocation)to avoid creating conflicting addresses.

[0040] The enhancement data, including announcements, resources, andtriggers, are transmitted (at 208) over the secondary link 20. A specialannouncement is also transmitted (at 210) with the enhancement data toindicate that ATVEF announcements associated with the A/V channel isavailable from a different source.

[0041] Separation of the enhancement data and the A/V content isillustrated in FIGS. 3A and 3B. As illustrated in FIG. 3A, each ofmultiple A/V channels A, B, and C includes audio data (A), video data(V), and enhancement data (D). The enhancement data of the multiplechannels are separated from the A/V content, as illustrated in FIG. 3B,so that the A/V content is transmitted without an ATVEF announcement,resource, or trigger. The enhancement data (D) of the different TVchannels are multiplexed onto a data network (e.g., the secondary link20) for transmission to or for retrieval by the receivers 16.

[0042] Thus, according to some embodiments of the invention, the ATVEFannouncements are not sent on the usual ATVEF announcement address andport. Instead, ATVEF announcements for a single A/V channel are madeavailable on their own announcement IP address. Instead of the regularATVEF announcements, a special announcement is transmitted on the ATVEFannouncement address and port to indicate that the ATVEF announcementsfor the TV channel have been re-directed. In other embodiments in whichATVEF is not used, announcements may refer to other indications ofpresence of ancillary information.

[0043] According to the current ATVEF Specification, an ATVEFannouncement sent on the ATVEF announcement address and port includes anattribute “a=type:tve” to identify that enhancement data is being sent.According to one embodiment of the invention, instead of including theattribute “a=type:tve,” the special announcement includes a differentidentifier attribute, e.g., “a=type:x-tvemult” or other predeterminedattribute. In one embodiment, the special announcement does not locateresource files and triggers for the enhanced TV program, but insteadlocates the announcement data for each TV channel. The specialannouncement is not recognized as a standard ATVEF announcement becauseof the lack of the “a=type:tve” attribute.

[0044] In one embodiment, the special announcement may include thefollowing information: TV network name (if any), located in a firststring, e.g., “a=x-tvnet:networknamestring”; TV station call letters,located in a second string, e.g., “a=x-tvstation:stationnamestring”;and/or major and minor channel numbers for tuning, located in a thirdstring, e.g., “a=x-tvtune:majorchannelnumber:minorchannelnumber”. Theinformation of the fields in the special announcement may be used to tiethe special announcement to a particular TV channel through anelectronic program guide or other channel mapping mechanism that may bemade available to the receiving system.

[0045] Referring to FIG. 7, a process according to one embodimentperformed by the controller 120 (under control of the SA routine 136and/or enhancement routine 138 in each receiver 16, 17, or 19 isillustrated. On the receiving side, the controller 120 determines if oneor more special announcements have been received (at 302) on thepredetermined ATVEF SDP address and port. Using the strings listedabove, the controller 120 processes the special announcements until onefor the currently tuned A/V channel is found (at 304). It then uses thespecial announcement to find the IP address and port for the ATVEFannouncements for the currently tuned channel (at 306). At this point,the ATVEF announcements that normally would have been transmitted overthe transport medium 22 along with the A/V content for the tuned TVchannel have been located. If the ATVEF announcement or announcementsare found, then the identified ATVEF announcements are processed (at310) to locate resource files and triggers. Otherwise, an error isindicated (at 312).

[0046] The processing performed by the controller 120 (at 310) may beperformed in one of various ways. In one embodiment in which the SAroutine 136 is part of the enhancement routine 138, the controller 120in the receiver 16 may directly access the ATVEF announcements locatedat the indicated IP address, from which the resource and trigger filesmay be located.

[0047] In an alternative embodiment in which the SA routine 136 andenhancement routine 138 are separate, the SA routine 136 first processesreceived special announcements. Based on the currently tuned A/Vchannel, the SA routine 136 identifies the one or more announcementsassociated with the tuned channel and retransmits or redirects them ontothe expected ATVEF IP address and port so that the enhancement routine138 can properly process the ATVEF announcements. The enhancementroutine 138 can then proceed to locate the resource and trigger streambased on the received ATVEF announcements. In this alternativeembodiment, the enhancement routine 138 need not be modified—instead,the responsibility of processing special announcements is placed on theSA routine 136. An advantage of this alternative embodiment is thatexisting receiving systems may be easily retrofitted with the SA routine136 by simply loading the component 136 from storage media (such asfloppy diskettes or CD or DVD media) or down-loading the component 136from a data network (such as the Internet).

[0048] Referring to FIGS. 4 and 5, special announcements NA for channelsB1, B2, and B3, received by the receiving system contain pointers to IPaddresses of the ATVEF announcements AAB1, AAB2, and AAB3 for channelsB1, B2, and B3, respectively. Assuming that channel B2 is the onecurrently tuned, the controller 120 (under control of the SA routine136) in the receiving system identifies the received specialannouncement NA for channel B2. From information in the specialannouncement NA, the controller 120 may locate the announcements AAB2associated with channel B2 for retransmission to the ATVEF announcementaddress and port. Upon retransmission of the ATVEF announcements AAB2 tothe expected IP address and port, resource and trigger files located bythe announcements AAB2 may then be conventionally processed by theenhancement routine 138.

[0049] Thus, a system has been described in which enhancement dataassociated with multiple TV programs or channels may be sent as a groupto one or more receivers. A predetermined indication (e.g., a specialannouncement) may be used to identify the location of ATVEFannouncements for enhancement data of the tuned A/V channel. The ATVEFannouncements may then be received and processed to obtain locations ofresource and trigger files.

[0050] Some embodiments of the invention may include one or more of thefollowing advantages. Enhancement data for multiple channels or programsmay be carried over a general purpose data network separately from theA/V content transport medium. This provides greater flexibility in howthe enhancement data may be transmitted. For example, if the transportmedium for delivering the A/V content does not have sufficient bandwidthfor sending large amounts of enhancement data, the separate channel mayprovide a mechanism of increasing that bandwidth. In cases where the A/Vcontent is transmitted over an analog transport medium (such as an NTSCmedium), delivering enhancement data over a separate channel such as aDOCSIS link, the Internet, or other communications link, avoids theexpense of employing a VBI data decoder in each receiver. Additionally,the viewer may be able to watch the enhancement data portion of the TVprogram separately from the A/V content if the viewer has a separate TVand personal computer.

[0051] Further embodiments of the invention may include transmissionsources to transmit A/V content other than TV content. Ancillaryinformation associated with such A/V content may be similarly madeavailable over a separate link.

[0052] Various software or firmware (formed of modules, routines, orother layers, for example) may be stored or otherwise tangibly embodiedin one or more machine-readable storage media in the informationdelivery system. Storage media suitable for tangibly embodying softwareand firmware instructions may include different forms of memoryincluding semiconductor memory devices such as dynamic or static randomaccess memories, erasable and programmable read-only memories (EPROMs),electrically erasable and programmable read-only memories (EEPROMs), andflash memories; magnetic disks such as fixed, floppy and removabledisks; other magnetic media including tape; and optical media such as CDor DVD disks. The instructions stored in the one or more storage mediawhen executed cause the information delivery system to performprogrammed acts.

[0053] The software or firmware can be loaded into the informationdelivery system in one of many different ways. For example, instructionsor other code segments stored on one or more storage media ortransported through a network interface card, modem, or other interfacemechanism may be loaded into the system 10 and executed to performprogrammed acts. In the loading or transport process, data signals thatare embodied as carrier waves (transmitted over telephone lines, networklines, wireless links, cables and the like) may communicate theinstructions or code segments to the information delivery system.

[0054] While the invention has been disclosed with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thetrue spirit and scope of the invention.

What is claimed is:
 1. A method of communicating television content andenhancement data including announcements, comprising: receiving thetelevision content associated with multiple television channels over atransport medium; receiving enhancement data associated with themultiple television channels that have been multiplexed onto a separatedelivery mechanism, announcements in the enhancement data being expectedat a first location; receiving one or more special indications at thefirst location indicating that announcements are available on theseparate delivery mechanism, the one or more special indicationsidentifying locations of the announcements associated with particulartelevision channels; determining a location of an announcement based ona special indication associated with a currently tuned televisionchannel; and processing the announcement of the currently tunedtelevision channel.
 2. The method of claim 1, wherein the processingincludes processing announcements according to an Advanced TelevisionEnhancement Forum Specification.
 3. The method of claim 1, wherein theone or more special indications are received on the separate deliverymechanism.
 4. The method of claim 1, wherein receiving the enhancementdata over the separate delivery mechanism includes receiving theenhancement data including the announcements on a data-only transportstream program.
 5. The method of claim 1, wherein receiving theenhancement data over the separate delivery mechanism includes receivingthe enhancement over a separate communications link.
 6. The method ofclaim 1, further comprising receiving the announcements at locationsdifferent from the first location.
 7. The method of claim 6, whereinreceiving the announcements includes receiving the announcements at anInternet Protocol address and port different from an expectedannouncement Internet Protocol address and port.
 8. A system capable ofcommunicating audio/video content, comprising: a receiver adapted totune to an audio/video program over a transport medium; a device adaptedto receive announcement data associated with the tuned audio/videoprogram directed to a first location and to receive a specialannouncement directed to the second location, the special announcementindicating availability of the announcement data associated with thetuned audio/video program; and a controller adapted to redirect theannouncement data to a second location.
 9. The system of claim 8,wherein the second location includes an address and port for receivingannouncements according to an Advanced Television Enhancement ForumSpecification.
 10. A method of communicating audio/video programs,comprising: receiving the audio/video programs over a transport medium;receiving a plurality of ancillary information streams associated with aplurality of audio/video programs over a separate delivery mechanism,announcements in the ancillary information streams being expected at afirst location; receiving a predetermined indication at the firstlocation; tuning to one of the audio/video programs; and identifying alocation of the announcement of an ancillary information streamassociated with the tuned audio/video program based on the predeterminedindication.
 11. A method of communicating audio/video content andenhancement data, comprising: transmitting the audio/video content overa transport medium; multiplexing enhancement data includingannouncements associated with multiple audio/video programs fortransmission over a separate delivery mechanism; and transmitting apredetermined indication over the separate delivery mechanism to a firstlocation at which the announcements in the enhancement data areexpected, the predetermined indication being associated with one of theaudio/video programs and identifying a location other than the firstlocation of one or more announcements associated with the oneaudio/video program.
 12. The method of claim 11, further comprisingmulticasting the enhancement data and predetermined indications to aplurality of receivers.
 13. The method of claim 11, wherein theenhancement data is according to an Advanced Television EnhancementForum Specification.
 14. The method of claim 13, wherein the firstlocation includes an IP address and port at which announcements areexpected to arrive.
 15. A system capable of receiving audio/videocontent over a transport medium and ancillary information over aseparate delivery mechanism, comprising: a first device adapted toreceive the audio/video content associated with a plurality ofaudio/video programs over the transport medium; a second device adaptedto receive one or more special indicators and a stream of ancillaryinformation portions associated with a plurality of audio/video programsover the separate delivery mechanism; and a controller adapted to locateone or more ancillary information portions associated with a tunedaudio/video program based on information in a special indicatoridentified with the tuned audio/video program, wherein the ancillaryinformation portions include announcements, and the special indicatorsinclude data identifying locations of the one or more announcements. 16.The system of claim 15, wherein the ancillary information is accordingto an Advanced Television Enhancement Forum Specification.
 17. Thesystem of claim 16, wherein the announcements are expected at anannouncement IP address and port.
 18. The system of claim 15, whereinthe first and second devices may include different parts of a softwareroutine.
 19. A system for transmitting audio/video content andannouncement information portions, comprising: a first unit adapted totransmit audio/video content over a transport medium; a controlleradapted to combine announcement information portions associated with aplurality of audio/video programs for transmission; and a second unitadapted to transmit the combined announcement information portions witha special indicator associated with an audio/video program, the specialindicator being transmitted to a first location at which theannouncement information portions are expected, the special indicatoridentifying locations of the announcement information portions.
 20. Thesystem of claim 19, wherein the announcement information portionsinclude announcements according to an Advanced Television EnhancementForum Specification.
 21. An article including one or moremachine-readable storage media containing instructions for communicatingaudio/video programs in a system, the instructions when executed causinga device in the system to: receive the audio/video programs, eachaudio/video program including at least one of audio data and video data,over a transport medium from a source; receive a stream of ancillarydata portions including announcements associated with a plurality ofaudio/video programs over a separate delivery mechanism; tune to one ofthe audio/video programs; receive a predetermined indicator associatedwith the tuned audio/video program at a first location; and identify asecond location of one or more announcements associated with the tunedaudio/video program based on the predetermined indicator.
 22. Thearticle of claim 21, the one or more storage media containinginstructions that when executed cause the system to receive audio/videoprograms including television content associated with a plurality oftelevision channels.
 23. The article of claim 21, the one or morestorage media containing instructions that when executed cause thesystem to receive ancillary data portions including enhancement dataaccording to an Advanced Television Enhancement Forum Specification.